The invention relates generally to thermal printers, and more particularly to thermal printers having reversible ribbons and methods therefor.
Thermal printers are known generally and used widely, for example to print variable information including lot codes, bar-codes, time and date, and other information on products and packaging, referred to herein as a web or substrate, in coding and marking operations. These printers comprise generally a thermal print head that transfers ink from a carrier, also known as a ribbon, disposed between the web and print head, which may be movable away from the ribbon when not printing. The ribbon is usually advanced, or dispensed, intermittently from a supply spindle to a rewind spindle, for example by an electrically or pneumatically driven feed roller or other known ribbon transfer means.
In some thermal printing operations, printing occurs while the web moves relative to the thermal printer, and thus it is necessary for the ribbon to move generally at the same speed as the web during ink transfer. A short time interval however is required to accelerate the ribbon from a stand-still to the web speed prior to printing. This time interval, or delay, depends generally on the speed of the web and also on the capacity of the ribbon transfer means, and results in only partial usage of the ribbon. More particularly, dispensed ribbon advanced beyond the print head while the ribbon accelerates up to the web speed prior to printing is unused, and thus wasted. Moreover, increased web speeds, which improve productivity, cause even greater ribbon waste since more time is required for the ribbon to accelerate up to the web speed. The ribbon is a costly consumable in coding and marking operations, and therefore it is desirable to utilize ribbon as efficiently as possible.
The present invention is drawn toward advancements in thermal printers.
An object of the invention is to provide novel thermal printers and methods therefor that overcome problems in the art.
Another object of the invention is to provide novel thermal printers and methods therefor that are reliable and economical.
Another object of the invention is to provide novel thermal printers and methods therefor that use ribbon more efficiently.
Another object of the invention is to provide novel thermal printers and methods therefor capable of reversing the direction that the ribbon is fed or dispensed.
A further object of the invention is to provide novel thermal printers and methods therefor that are operated electrically without the need for a compressed air supply.
Yet another object of the invention is to provide novel thermal printers and methods therefor that operate reliably in greasy printing environmental conditions.
A more particular object of the invention is to provide novel thermal printers that transfer print from a ribbon onto a moving web and methods therefor comprising generally dispensing the ribbon from a supply spindle with a feed roller rotating in a first direction, winding the ribbon on a rewind spindle when dispensing ribbon from the supply spindle, and reversing the ribbon dispensing direction before or after printing by rotating the feed roller in a second direction opposite the first direction to rewind unused ribbon.
These and other objects, aspects, features and advantages of the present invention will become more fully apparent upon careful consideration of the following Detailed Description of the Invention and the accompanying Drawings, which may be disproportionate for ease of understanding, wherein like structure and steps are referenced generally by corresponding numerals and indicators.